Aeroponic plant growth apparatus and method

ABSTRACT

Aeroponic plant growing apparatus which includes an elongate vertically oriented plant chamber having a plurality of plant receiving apertures through its side wall. Stationed at the top of the chamber are one or more spray nozzles through which nutrient solution is sprayed into the chamber, thereby wetting the roots of the plants stationed in the apertures. The apparatus includes structure by which fresh atmospheric air is inducted into the chamber and stagnant air is exhausted during the spraying of the plant roots. In a preferred alternative the motive energy for this air induction into the plant chamber is provided by the spray nozzle(s) and an air induction manifold cooperates with the spray nozzle(s) to establish a low pressure Venturi zone therebetween.

BACKGROUND OF THE INVENTION

The present invention relates broadly to the soilless cultivation ofplants and more particularly relates to an improved apparatus and methodfor the aeroponic cultivation of plants.

Hydroponic growth apparatus, either for decorative purposes in a home orfor commercial purposes such as in a greenhouse, are known. Typical ofvarious U.S. patents disclosing such apparatuses are: U.S. Pat. No.4,033,072, to Kobayashi et al.. dated Jul. 5, 1977; U.S. Pat. No.4,218,847, to Leroux, dated Aug. 26, 1980; U.S. Pat. No. 4,454,684, toO'Hare, dated Jun. 19, 1984; U.S. Pat. No. 4,756,120, to Arledge, datedJul. 12, 1988; U.S. Pat. No. 4,951,416, to Gutridge, dated Aug. 28,1990; and U.S. Pat. No. 4,986,027, to Harvey, dated Jan. 22, 1991. Ingeneral, according to the article "Hydroponics: Soilless Gardening",appearing in Volume 5 of New Illustrated Encyclopedia of Gardening, TheGreystone Press, New York, N.Y., 1960, "hydroponic" plant culture can bebroadly defined as the cultivation of plants in a soilless media whereinsubstantially the entirety of nutrients supplied to the plant roots isaccomplished by wetting of the plant roots with an appropriate aeratednutrient solution containing, as solutes, the necessary plant nutrients.Thus, the plant roots in hydroponic plant cultures can be supplied by apool of nutrient solution in which the plant roots are directly immersedor by wetting of a porous inert aggregate material such as sand, gravel,vermiculite, expanded mica, crushed stone, cinders, bricks, glass beads,ground lava and the like and within which aggregate material the plantroots reside. The nutrient solutions utilized in the hydroponiccultivation of plants usually contain solutes comprising not only theprimary plant growth elements of nitrogen, potassium and phophorous, butalso the micronutrient or trace elements essential to the healthy growthof the particular plant species involved, such as calcium, magnesium,boron, iron, manganese and the like. Additionally, the nutrient solutionis often aerated such that the solution applied to the plant rootscontains adequate dissolved oxygen to sustain plant growth. Moreover,the p^(H) of the nutrient solution is normally controlled to within theoptimum range for the particular plant species involved. In respect ofhydroponic pool systems, one of the methods commonly employed isgenerally termed as the "flood and drain" method. Here, a horizontallydisposed tray containing the roots of the growing plants is cyclicallyflooded with a nutrient solution. Upon completion of the flood cycle thetray is drained into a recycle receptacle for subsequent recycle of thenutrient solution at the next flood cycle. The drain cycle is animportant element of the system since the plant roots, if allowed toremain continuously immersed in the nutrient solution, would be subjectto the danger of suffocation. Such "flood and drain" hydroponic systems,due to the physics and geometry of bulk water flow, inherently requirethat the plants be arranged in a planar array relative to the tray,thereby limiting the number of plants which can be grown per unitsurface area thereof.

It has been found that hydroponic plant culture often results in fasterplant growth and maturation and greater flower or fruit yields relativeto conventional field and greenhouse soil culture methodologies. It isgenerally theorized that these benefits flow from the fact that, ascompared to conventional soil culture methodologies, the plant roots inhydroponic culturing are substantially relieved of the energy-consumingburden of searching and growing through nutrient-poor soils in order toobtain adequate plant nutrition. Thus, in hydroponic plant cultivation,the plant energy normally devoted to root growth is, instead, at leastpartially made available to the growth and maturation of the plant,thereby resulting in earlier maturation and more prolific flower orfruit yield. In support of this theory it is often found that the rootsystems of mature flowering or fruiting plants grown hydroponically aresubstantially shorter or of lesser overall mass than those of similarplants grown in conventional soils.

"Aeroponic" plant culture refers to a sub-genus of hydroponics in whichneither a root supportive particulate media nor a root immersion pool ofnutrient solution is employed. Instead, in aeroponic plant culture, theplants are generally supported in a vertically oriented elongate chamberwhose side wall is perforated with a plurality of plant site aperturesto receive the plants and within which chamber the plural plant rootsreside suspended, in free space. The foliage of the plants is, ofcourse, stationed exterior of the chamber, thereby to receive light. Anutrient solution is sprayed cyclically or continuously from the top ofthe chamber, upon the bare plant roots contained therewithin. As in theflood and drain hydroponics system, excess nutrient spray solution maybe collected from the bottom of the chamber, any particulate matterfiltered and/or settled out therefrom, and recycled to the spraynozzles. Aeroponic plant culture provides a number of advantages overother hydroponic systems. Firstly, no aggregate material is utilized,thereby providing obvious expense, weight, handling and clean-upadvantages. Secondly, because the plant roots remain bare, individualplants in an aeroponic system can usually be readily removed with theirroot systems intact. This becomes a particularly important feature intransplantation or where plant disease or infestation occurs and whereinremoval of the entirety of the diseased or pest ridden plants from thesystem, without residue, is highly desirable. Too, aeroponic cultivationpermits arrangement of the growing plants circumferentially andvertically about the root chamber, thereby permitting closer packing ofthe plant stock and more efficient use of nursery space than is affordedby the aforementioned flood and drain hydroponics system.

In accordance with the present invention, it has now been found that theplant growth and maturation rate advantages generally associated withthe hydroponic cultivation of plants over other forms of plant culturecan be even further improved in aeroponic systems when atmospheric airis affirmatively inducted into the root chamber of the aeroponic plantgrowing apparatus and stale air is exhausted therefrom, at least duringthe period of spraying of the plant roots with nutrient solution.

Beyond the foregoing, however, additional limitations and detrimentsrelating to prior art aeroponic cultivation apparatuses and techniqueshave also been addressed and resolved in at least certain preferredembodiments of the invention. For instance, in known aeroponic systems,little or no provision is made for the facile removal, replacement andchanging of sub-populations of plants whose root systems may have fallenprey to fungal, bacterial, viral or pest infestations or which plantsmay otherwise have been rendered of lesser quality of growth andmaturation than other plants in the system. In accordance with theinvention, however, an aeroponic growth system and method is providedwherein plural plants residing within said system may be quickly andconveniently removed, replaced and/or augmented.

OBJECTS OF THE INVENTION

It is a principal object of the present invention to provide novelapparatus for the aeroponic culture of plants.

It is another object of the present invention to provide novel apparatusfor the aeroponic culture of plants and which apparatus provides animproved root environment therefor.

It is yet another object of the present invention to provide novelsegmented apparatus for the aeroponic culture of plants whereinprovision is made for the facile removal and/or replacement of sectionsof plants living within the growing community thereof.

It is still another object of the invention to provide apparatus for theaeroponic culture of plants wherein populations of sickly or infectedplants may be effectively entirely removed and/or replaced from thesystem without leaving behind root elements of said sickly or infectedplants.

It is another object of the invention to provide aeroponic plant growthapparatus having improved means for supporting the plants grown therein.

It is yet another object of the invention to provide a novel method forgrowing plants aeroponically wherein the growth rate, maturation fruit-and/or flower-bearing yields thereof are maximized by control of theenvironment in which the roots of said plants are maintained.

Other objects and advantages of the present invention will, in part, beobvious and will, in part, appear hereinafter.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided an aeroponic growthapparatus broadly comprising:

(a) an essentially vertically oriented elongate plant chamber defined bya tubular side wall and having upper and lower ends, said side wallcomprising a plurality of plant receiving apertures therethrough;

(b) spray means comprising at least one spray nozzle stationed at theupper end of said chamber, said spray means being oriented to directliquid plant nutrient spray downwardly into the bore of said chamber andto thereby wet plant roots residing therewithin;

(c) means to induct atmospheric air into said chamber and to exhauststagnant air therefrom during operation of said spray means of (b); and

(d) means to deliver liquid plant nutrient solution to said spray meansof (b).

In accordance with one preferred embodiment of the apparatus of theinvention said plant receiving apertures are each provided with anintegral plant supporting unit extending exteriorly therefrom. Inanother preferred embodiment the plant receiving apertures are staggeredhelically and vertically about the side wall of the chamber so as tomaximize the number of plants which may be grown therein while providingadequate space for the foliage thereof. In still another preferredembodiment the bottom of the chamber is in open fluid communication witha receptacle positioned thereunder, said receptacle acting to collectexcess nutrient solution from said chamber and further comprising meansto deliver said recovered solution to said spray means.

In accordance with the novel aeroponic plant cultivation method of theinvention there is provided an elongate vertically oriented plantchamber defined by a tubular side wall and having plural plant receivingapertures through said side wall. Plural plants are installed in saidapertures with the roots thereof suspended within the plant root zonedefined by the interior space of said chamber. A plant nutrient solutionis sprayed downwardly from the top of the chamber and upon said roots,said spraying being undertaken continuously or, preferably, cyclically.During the course of said spraying of nutrient solution atmospheric airis affirmatively inducted into the plant root zone of said chamber whilestagnant air is exhausted therefrom. In a preferred embodiment of theprocess, excess sprayed nutrient solution is recovered, filtered and thethusly recovered solution recycled to the spraying step.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 hereof is a schematic side elevation of an aeroponic plant growthapparatus in accordance with a preferred embodiment of the invention.

FIG. 2 hereof is an enlarged, partially sectional, side view of certainof the elements of the apparatus of FIG. 1.

FIG. 3, hereof is a top sectional view of the apparatus of FIG. 2, takenthrough lines 2--2' thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring now to FIGS. 1 through 3, wherein like reference numeralsrefer to like structures, the apparatus of the invention broadlycomprises an essentially vertically oriented elongate plant chamber 1having a tubular side wall 2 and upper and lower ends 3 and 4,respectively. While said chamber 1 may be of any desired shape, such asin the nature of a jardiniere, I generally prefer that said chamber 1have an essentially constant cross section throughout its length andthat its cross section be of circular or polygonal geometry. With thisin mind, I have found that the chamber 1 can generally be readilyfabricated from commercially available low pressure plastic pipeelements and fittings. Moreover, the chamber 1 can be made up of pluraltubular chamber segments 5, 5' and which segments may be separablystacked or mounted one upon another in order to make up the overalllength of said chamber. The provision of this feature of stackability isof great benefit to the user in that it allows for easy adjustment ofthe overall length of the chamber 1, allows plants to be removed andreplaced in the system with great facility and further allows easytransfer of plants from one system to another, should the need or desirearise. It also substantially facilitates assembly and take down of theapparatus and cleansing of the interior of the chamber 1.

As can best be seen in FIG. 2, the side wall 2 of plant chamber 1comprises a plurality of plant receiving apertures 20 therethrough.Preferably, said apertures 20 are arranged in spaced array about thecircumference of each tubular chamber segment 5 or 5', as the case maybe, such that when said chamber segments are united, as in FIG. 1, theresulting arrangement of said apertures 20 in the chamber 1 are in ahelically and vertically staggered array. Said staggered arrangement ofthe apertures 20 tends to maximize the number of plants which can begrown in the chamber 1 while providing adequate exterior space to handlethe foliage of said plants as they grow to maturity. In addition, saidarrangement also tends to cause the foliage of the growing plants toeffectively obscure the chamber 1, thereby contributing to the overallattractiveness of the planting.

In another preferred embodiment, each plant receiving aperture 20 isprovided with an integral plant supporting element 18 extendingexteriorly of the side wall 2. It is the role of said plant supportingelement 18 to support the stem of the plant during its growth and,desirably, to urge the plant to maximally present its foliage to light.Where the chamber 1 is comprised of low pressure plastic pipe andfitting elements, I have found that one type of effective supportingelement 18 takes the form of a plastic 45° el plumbing fitting solventwelded to the corresponding aperture 20 such that the interior leg ofthe fitting extends generally horizontally and exteriorly of the sidewall 2 and the exterior leg of the fitting extends upwardly andexteriorly of the interior leg. Beyond this, such 45° el plumbingfittings are commercially available in which the juncture between theinterior and exterior legs of the el is radiused so as to smoothlytransition from one leg to the other thereof. Such smoothly radiused elsare preferred in the apparatus of the invention because they ease theplacement and removal of plants from the plant receiving apertures 20without substantial damage to the root systems thereof.

The upper end 3 of said chamber 1 is preferably closed to the exterioratmosphere by means of a closure member 10. Said closure member 10serves to preserve the humidity within the bore 6 defined by the tubularside wall 2 of the the chamber 1. In turn, said bore 6 constitutes theplant root receiving zone of the apparatus within which the plant rootsof the plants received into the apertures 20 are suspended throughoutthe growth and maturation of the plants.

Further, the upper end 3 of the plant chamber 1 comprises spray means 7stationed thereat, which spray means 7 includes at least one spraynozzle 14 adapted to receive and spray plant nutrient solutiondownwardly into the bore 6 of the chamber 1, thereby to wet the roots ofthose plants residing within the apertures 20 of the plant chamber 1with said solution. Obviously, depending upon the geometry anddimensions of said chamber 1, said spray nozzle(s) 14 can be singular orplural in number in order to effectively achieve the above result. Saidspray nozzle(s) 14 can be of the known pressure, bi-fluid or spinningdisk types and, while it is preferred that the spray effluent therefrombe in the fineness of a mist or aerosol, the fineness of the sprayeffluent is not a limitation in the present invention, it beingsufficient that the resulting spray from said nozzle(s) 14 wet the rootsof all plants suspended within the plant root chamber 1.

The present invention includes means by which to deliver nutrientsolution to the spray means 7. Said delivery means may be entirelyexternal to the apparatus of the invention, such as in the nature of apump, not shown, receiving nutrient solution from an external source anddelivering same to the spray nozzle(s) 14 of the apparatus throughappropriate tubular fluid commication(s) thereto or, more preferably,will be internal to the apparatus of the invention. In this regard, itis preferred that the lower end 4 of the plant chamber 1 be in openfluid communication with a collection receptacle 38 disposed thereunderand to which collection receptacle 38 the plant chamber 1 is detachablyconnected, such as through downspout 28. The collection receptacle 38comprises a fluid receptacle 31 having a cover 29 detachably securedthereto, the latter of which may take the form, for instance, of anexpansion coupling 29. Disposed across the lower end 4 of the chamber 1is filtration screen 26 which serves to filter solid matter from theexcess nutrient solution spray received from the plant chamber 1 andwhich screen 26 passes said thusly filtered excess nutrient solutioninto the collection receptacle 38 through downspout 28, cover 29 thenceinto the fluid receptacle 31. Collection receptacle 38 contains not onlythe excess nutrient solution spray collected from the plant chamber 1,but also make-up fresh nutrient solution which may be admitted through afill port 30 which is in fluid communication with downspout 28.Desirably, the fill port 30 is transparent, thus also serving as a sightport for viewing the level of nutrient solution contained in thecollection receptacle 38 and, further, comprises a removable cap 32 bywhich to avoid entry of undesired materials into the receptacle 31 andto prevent excess liquid evaporation therefrom. The collectionreceptacle 38 further includes a suitable electrically operated pump 40,shown in phantom, which may be mounted within the fluid receptacle 31and which pump 40 is in fluid communication with the nozzle(s) 14 ofchamber 1 such as through serially connected hoses 41, 36 and 42,respectively. Said pump and the tubular communication provided saidhoses thus serve as the prime means by which to supply nutrient solutionfrom the collection receptacle 38 to the spray means 7 of the apparatusof the invention. In this manner, the apparatus of the invention isrendered self-contained, thus avoiding the complexities and expenseinvolved in providing external means for providing the nutrient solutionto the spray means 7. Moreover, the relatively heavy mass provided bythe collection receptacle 38, pump 40 and its liquid nutrient contentsserve beneficially to physically stabilize the plant chamber 1detachably secured thereon.

In the above preferred construction of the invention it is furtherpreferred to provide means by which the fluid communication between theliquid nutrient supply means of the collection receptacle 38 and thespray means 7 of the detachable plant chamber 1 may be convenientlydisconnected and connected for such removal and reassembly of the plantchamber 1 to the collection receptacle 38 as may be found necessary ordesirable. In the apparatus of FIGS. 1 and 2 said means is provided by apair of externally and internally exposed hose barbs 34, 34' theinterior end of barb 34' being mounted in fluid communication with theinterior of fill port 30 and the interior end of barb 34 being mountedin fluid communication with the bore 6 of the lower end 4 of the plantchamber 1. Interposed between the exteriorly exposed ends of said barbs34, 34' and establishing fluid connection therebetween is a hose section36 which, due to its placement exterior of the apparatus, may be readilydetached and/or reattached at one or the other of its ends from eitherof the barbs 34, 34' thereby facilitating assembly and disassembly ofthe plant chamber 1 to and from the collection receptacle 38. Theinterior end of the barb 34 associated with the plant chamber 1 isconnected to tubular hose communication 42 supplying spray means 7 whilethe interior end of the barb 34' associated with the fill port 30 isconnected to the hose 41 communicating with the discharge of thenutrient liquid supply pump 40 mounted within the receptacle 31.

In another preferred embodiment of the invention the plant chamber 1and, if present, the collection receptacle 38 to which said chamber 1 isdetachably secured, are mounted on a castered dolly 46, thereby toprovide facility in moving the aeroponic apparatus and/or in rotatingsame such as to adjust the plants growing therein with respect toprevailing incident light conditions.

A vital element in the apparatus of the invention and its method is theprovision of means by which atmospheric air, i.e. ambient air from theexternal atmosphere, is affirmatively inducted into the bore 6 of plantchamber 1 during operation of said spray means 7 while stagnant air isexhausted therefrom. Any suitable apparatus for carrying out these dualfunctions can be employed, such as an electrically powered blower or fanstationed at the upper end 3 of the chamber 1 and which fan or blower isadapted to receive atmospheric air and introduce it into the bore 6during nutrient solution spray operations while stagnant air from withinthe bore 6 is exhausted, such as through exhaust holes or aperturesprovided at or near the bottom 4 of the chamber 1. However, in theinterests of simplicity of equipments and conservation of energy I muchprefer that the air induction and exhaustion scheme utilized in theinvention be passive in nature and utilize the motive energy provided bythe flow of liquid through the spray nozzle(s) 14. Accordingly, as shownin FIGS. 1-3 hereof and with particular reference to FIGS. 2 and 3, in apreferred embodiment of the invention the nozzle 14 is of the bi-fluidor pressure type and the means utilized to induct fresh atmospheric airfrom the external environment into the bore 6 comprises a tubularelement 16 defining an air induction manifold which is transverselydisposed across the upper end 3 of chamber 1 and the ends of whichtubular element 16 are in open communication with the externalatmosphere through inlet apertures 15. Spray nozzle 14 is centrallymounted through the upper surface of said tubular element 16. Located onthe bottom surface of said tubular element 16 is an aperture 17 whichsurrounds and is suitably spaced from the discharge end of spray nozzle14 so as to define an annular low pressure Venturi zone therebetween.Thus, flow of liquid nutrient solution from the nozzle 14 during thenutrient spray cycle results in the creation of a low pressure zone inthe region of the aperture 17 whereby atmospheric air is inductedthrough said apertures 15 into the tubular element 16 and is thenprojected downwardly into the bore 6 through the aperture 17. Exhaust ofstagnant air from the bore 6 is achieved during the nutrient solutionspray cycle by means of apertures 13 communicating with the exterioratmosphere through the material of the upper end 3 of the chamber 1 andin a plane which substantially corresponds to the plane of theatmospheric inlet apertures 15. Thus, as fresh atmospheric air isintroduced into the bore 6 through inlet apertures 15 during thenutrient solution spray cycle, the volume of stagnant air as may havepreviously existed within said bore 6 is exhausted to the exterioratmosphere through apertures 13 by displacement of the previouslyexisting stagnant air mass by the thusly introduced fresh atmosphericair.

In accordance with the aeroponic plant growing method of the presentinvention utilizing the apparatus hereof, plants are stationed withinthe plural apertures 20 of the elongate plant chamber 1, the roots ofsaid plants being suspended within the bore 6 while the plant foliage ispositioned exteriorly of the plant chamber 1. Having thus beenpositioned, the spray means 7 is activated such as to wet the plantroots contained within the bore 6 with a suitable plant nutrientsolution. During the time of said spraying of the plant roots with saidnutrient solutionj. affirmative induction of fresh atmospheric air intothe bore 6 of the plant chamber 1, along with concomitant exhaustion ofstagnant air therefrom, takes place. While the wetting of said plantroots by spray means 7 can generally be undertaken continuouslythroughout the daylight when plants actively grow, respire and mature,it is generally desirable that said wetting of the plant roots by saidspray means 7 be undertaken cyclically with a rest period interposedbetween said wetting cycles. While the durations of the spray and restperiods in these preferred cyclic operations are subject to considerablevariation and are at least somewhat affected by such considerations asthe ambient temperature and relative humidity, I have generally foundthat use of nutrient solution spray cycles in accordance with the methodof the invention of up to about 15 minutes in duration and with restcycles of up to about 45 minutes interposed therebetween constituteeffective root wetting/rest cycles within which the methodology of thepresent invention may be effectively practiced and the benefits thereofrealised.

Utilizing the above precepts of construction and operation I havesuccessfully aeroponically grown various vegetable plants, such asvarious tomato and pepper species, to bountiful yields in apparatuseswhich, unless expressly noted below, were of the type depicted in thedrawings hereof and described above. Each said apparatus comprised anelongate plant chamber 1 of circular cross section, having anessentially uniform bore 6 diameter of about 6 inches and being composedof a vertically stacked array of four tubular segments 5, 5', each saidsegment 5 or 5', as the case may be, being composed of polyvinylchloridepipe and suitable coupling fittings, having an overall length of 6inches and having five plant apertures 20 arranged radially about thecircumference thereof. Each said plant aperture 20 additionallycomprised a plant supporting element 18 in the nature of an arcuatelyshaped tubular polyvinychloride 45° el solvent welded to and extendingoutwardly and upwardly therefrom. In the assembled state, the resultingtwenty apertures 20 of the chamber 1 were conformed into a verticallyand helically staggered array. A single pressure-operated full conespray nozzle 14, having a rated spray capacity of 1.4 gal./minute @10p.s.i. and an included spray angle of about 120°, was directeddownwardly and centrally into the top of the bore 6 of said chamber 1,said nozzle being a Model 1/4 HHPVC14W, manufactured by Spraying SystemsCompany of Wheaton, Ill. The nozzle 14, whose discharge end had anoutside diameter of 1/2 inch, was mounted into the center of the uppersurface of a tubular manifold element 16 composed of a straight sectionof 1/2 inch I.D. polyvinychloride pipe transversely disposed across adiameter of the uppermost segment 5'. The respective ends of saidmanifold element 16 were established in open communication with theexternal atmosphere through a pair of diametrically opposed inletapertures 15, each of 1/2 inch diameter. Essentially coplanar withrespect to said inlet apertures 15 and disposed on a diameter of theuppermost segment 5' 90° thereto were two diametrically opposed exhaustapertures 13, each said aperture 13 being of 1/2 inch diameter. Thedischarge end of said nozzle 14 was centrally directed through anaperture 17 located in the bottom surface of the manifold element 16,said aperture 17 having a diameter of 5/8 inch, thereby providing anannular low pressure Venturi zone of about 1/16 inch between saidaperture 17 and the discharge end of said nozzle 14. The nozzle 14 wassupplied with a nutrient solution by means of an electrically poweredsubmersible pump 40 contained within the receptacle 38 to which thechamber 1 was detachably affixed. The pump was a Model NK-1,manufactured by Little Giant Pump Company, of Oklahoma City, Okla. andwhich pump 40 had a rated capacity, at open discharge, of 210gallons/per/hour. Fluid communication between the discharge of said pump40 and said nozzle 14 was achieved by serially connected 1/2 inch I.D.hoses 41, 36 and 42, respectively. A timer was interposed between thepump 40 and its electric power source, thereby to provide the capabilityto operate the pump cyclically, at timed intervals.

In operations of the above-described apparatuses seedling plants wereinitially installed in each apparatus through each of the twenty plantsupport elements 18 thereof and into said apertures 20, the roots ofsaid plants thus being suspended within the bore 6. Then, by appropriatesetting of the timer the roots of the thusly disposed growing plantswere cyclically wetted during the daylight hours throughout the lengthof their growth and maturation by spraying of said nutrient solutionthrough the spray nozzle 14 for a spray period of 15 minutes, followedby a rest period of about 45 minutes. Affirmative induction ofatmospheric air into the bore 6 during the spray periods wasdemonstrated by holding a lighted candle near each of the air inductioninlet apertures 15 and noting that the candle flame and its smoke wereinducted thereinto. Using this candle demonstration technique theexhaustion of stagnant air from the bore 6 during said spray periods wassimilarly noted.

While the foregoing description demonstrates certain preferredembodiments of the apparatus of the present invention and of techniquesfor the implementation and use thereof it should be noted, recognizedand understood that said description is not to be construed as limitingin nature because many obvious changes, modifications and variations maybe made in the above description of the apparatus and method withoutdeparting from the essential scope, spirit or intention of theinvention. For instance, while the plant chamber 1 and/or the collectionreceptacle 38 of the above-described apparatus have each beenhereinbefore particularly described as desirably being composed of aplastic material, it is obvious that one, the other, or both of saidelements of the invention can also be composed of a ceramic, metallic orany other material suitable to the intended tasks thereof. Moreover, theplant chamber 1 need not be of circular cross section and need not be ofconstant cross section throughout its length. Also, the air inductionmanifold need not take the specific form of the tubular element 16described above, it being obvious that many alternative forms of suchair induction manifolds will suggest themselves to those of ordinaryskill in the art of fluidics and, further, that the specific design ofsuch manifolds may also be dictated by the use of multiple nozzles 14.It will also be obvious that the active element to induct atmosphericair and exhaust stagnant air from the bore 6 need not be stationed atthe induction side of the apparatus of the invention. For instance, saidelement can also be in the nature of an exhaust fan or blower stationedexternally of the exhaust side of the arrangement, thereby to draw freshair into the bore 6 through a suitably disposed air induction inletwhile drawing stagnant air through the exhaust outlet thereof.Accordingly, it is intended that the invention is to be limited only bythe scope of the appended claims.

What is claimed is:
 1. Aeroponic plant growing apparatus comprising:(a)an essentially vertically oriented elongate plant chamber having upperand lower ends and a tubular side wall, said chamber having a boredefining a plant root receiving zone and said side wall comprising aplurality of plant receiving apertures therethrough; (b) spray meanscomprising at least one spray nozzle stationed at the upper end of saidplant chamber, said spray means being oriented to spray liquid plantnutrient solution downwardly through the bore of said chamber, therebyto wet plant roots residing within said zone; (c) means to supply liquidplant nutrient solution to said spray means; and (d) means to inductatmospheric air and to exhaust stagnant air from said chamber duringoperation of said spray means.
 2. Aeroponic plant growing apparatus inaccordance with claim 1 wherein said means to induct atmospheric airinto said chamber comprises an air induction manifold in opencommunication with atmospheric air, said manifold being conformed andarranged with respect to said at least one spray nozzle so as toestablish a Venturi effect low pressure zone therebetween, wherebyoperation of said at least one nozzle induces flow of atmospheric airinto said chamber through said manifold.
 3. Aeroponic plant growingapparatus in accordance with claim 1 wherein said essentially verticallyoriented elongate chamber comprises a plurality of tubular segmentsseparably mounted one upon the other.
 4. Aeroponic plant growingapparatus in accordance with claim 1 comprising plant supporting meansintegral with and extending exteriorly of each said plant receivingaperture.
 5. Aeroponic plant growing apparatus in accordance with claim4 wherein each said plant supporting means is in the nature of a tubular45° el having an interior leg extending generally horizontally andexteriorly of the plant receiving aperture associated therewith and anexterior leg extending upwardly and exteriorly of said interior leg. 6.Aeroponic plant growing apparatus in accordance with claim 5 wherein thejuncture between the interior and exterior legs of each said el isarcuate.
 7. Aeroponic plant growing apparatus in accordance with claim 1wherein the bottom end of said chamber is in fluid communication with acollection receptacle disposed thereunder, said receptacle therebycollecting excess sprayed nutrient solution therefrom.
 8. Aeroponicplant growing apparatus in accordance with claim 7 wherein saidcollection receptacle includes means to supply nutrient solutiontherefrom to said spray means.
 9. Aeroponic plant growing apparatus inaccordance with claim 8 wherein said supply means comprises a pumphoused within said collection receptacle and a tubular communicationbetween said pump and said spray means.
 10. Aeroponic plant growingapparatus in accordance with claim 7 wherein said elongate chamber isremovably secured to said collection receptacle.
 11. Aeroponic plantgroving apparatus in accordance with claim 7 wherein said collectionreceptacle is mounted on a castered dolly.
 12. Aeroponic plant growingapparatus in accordance with claim 1 wherein said elongate chamber is ofcircular cross section.
 13. Aeroponic plant growing apparatus inaccordance with claim 1 wherein said elongate chamber is of polygonalcross section.
 14. Aeroponic plant growing apparatus in accordance withclaim 1 wherein said plurality of plant receiving apertures are arrangedin a helically and vertically staggered array about the side wall ofsaid plant chamber.